The present invention relates to a mobile communication system; and, more particularly, to an apparatus and method for canceling pilot signal transmitted from neighbor base stations and a computer readable record medium for executing the same method.
International Mobile Telecommunication-2000 (IMT-2000) supporting a mobile multimedia terminal requires that a bandwidth of a downlink transmission channel is broader than an uplink transmission channel in order to provide various Internet services containing multimedia contents.
For increasing a bandwidth of a downlink transmission channel, a demodulator of the mobile station needs to be well operatable in a low signal-to-noise ratio (Eb/No) and the demodulator should be tolerable of interference signals.
A pilot signal is transmitted for synchronization of timing between the mobile station and the base station to which the mobile station belongs. The pilot signals from neighbor base stations act as interference signals to the mobile station. The pilot signal of the base station is removed by demodulation due to orthogonal characteristic in the mobile station. However, the pilot signal from the neighbor base station is not perfectly removed and remained as a strong interference signal.
It is, therefore, an object of the present invention to provide an apparatus and method of a demodulator in a mobile station canceling a pilot signal transmitted from neighbor base stations for increasing a bandwidth of downlink transmission channel and improving the demodulator operatable in low signal-to-noise ratio (Eb/No).
In accordance with an aspect of the present invention, there is provided An apparatus for canceling pilot signals from neighbor base stations to a mobile station, the apparatus including: search unit for finding signals transmitted from neighbor base stations; estimation unit for generating an estimated interference signal by estimating channels to detect characteristics of wireless channels of the neighbor base stations; cancellation unit for canceling an interference signal in the received signal based on the estimated interference signal outputted from the estimation unit and signals received from the neighbor base stations; and delay unit for delaying input of the received signal to the cancellation unit as much as time necessary for generating the estimated interference signal in the estimation unit.
In accordance with another aspect of the present invention, there is also provided a method for canceling pilot signals of neighbor base stations, including the steps of: a) searching signals transmitted from the neighbor base stations to a mobile station by analyzing a received signals; b) generating an estimated interference signal by estimating channels of the base stations to detect characteristics of wireless channels of the neighbor base stations and generating the estimated interference signal; and c) canceling an interference signal calculated by using the estimated interference signal and the signals received from the neighbor base stations.
In accordance with another aspect of the present invention, there is also provided a computer readable record medium storing instructions for implementing method for canceling pilot signals transmitted from neighbor base stations, the method including steps of: a) searching signals transmitted from the neighbor base stations to a mobile station by analyzing a received signals; b) generating an estimated interference signal by estimating channels of the base stations to detect characteristics of wireless channels of the neighbor base stations and generating the estimated interference signal; and c) canceling an interference signal calculated by using the estimated interference signal and the signals received from the neighbor base stations.